Abstract: The presence or absence of a property in a computer subsystem is determined using a multiple input shift register (MISR). A subsystem device operates on predetermined test data to produce output data. The MISR operates on the output data to produce a final test value dependent on the output data. The property has a known final MISR value associated with the device under test and the test data. The MISR final test value is read and compared to the known final value for the property. If the two values are the same, the property exists in the system. In a second embodiment, a property from among a set of known possible properties or variations of a property is determined. In a specific application of the second embodiment, the length of a serial access memory (SAM) portion of a video random access memory (VRAM) is determined.